The mammillothalamic tract (MMT) (also mammillary fasciculus, mammillothalamic fasciculus, thalamomammillary fasciculus, bundle of Vicq d'Azyr) is an efferent pathway of the mammillary bodies which project to the anterior nuclei of the thalamus. The mammillothalamic tract is part of the

Papez circuit The Papez circuit ,Livingston, Kenneth E. '. U.S. National Library of Medicine, 1981 or medial limbic circuit, is a neural circuit for the control of emotional expression. In 1937, James Papez proposed that the circuit connecting the hypothalam ...

(involved in

spatial memory In cognitive psychology and neuroscience, spatial memory is a form of memory responsible for the recording and recovery of information needed to plan a course to a location and to recall the location of an object or the occurrence of an event. Sp ...

), starting and finishing in the

hippocampus The hippocampus (: hippocampi; via Latin from Ancient Greek, Greek , 'seahorse'), also hippocampus proper, is a major component of the brain of humans and many other vertebrates. In the human brain the hippocampus, the dentate gyrus, and the ...

.Shah, A., Jhawar, S. S., & Goel, A. (2012). Analysis of the anatomy of the Papez circuit and adjoining limbic system by fiber dissection techniques. rticle Journal of Clinical Neuroscience, 19(2), 289-298. . The fibers of the MMT are heavily myelinated. It arises from the medial and lateral nuclei of the mammillary bodies, and from fibers that are directly continued from the fornix of the hippocampus. It connects the mammillary bodies to the dorsal tegmental nuclei, the ventral tegmental nuclei, and the anterior thalamic nuclei.

Structure

Axons divide within the gray matter; the thicker fibres form the MTT while the finer branches descend as the mammillotegmental fasciculus. The MTT spreads fan-like as it terminates in the

medial dorsal nucleus The medial dorsal nucleus (or mediodorsal nucleus of thalamus, dorsomedial nucleus, dorsal medial nucleus, or medial nucleus group) is a large nucleus in the thalamus. It is separated from the other thalamic nuclei by the internal medullary lam ...

. The axons from these nuclei form part of the

thalamocortical radiations In neuroanatomy, thalamocortical radiations, also known as thalamocortical fibers, are the efferent fibers that project from the thalamus to distinct areas of the cerebral cortex. They form fiber bundles that emerge from the lateral surface of t ...

Function

The mammillary bodies directly or indirectly connect to the

amygdala The amygdala (; : amygdalae or amygdalas; also '; Latin from Greek language, Greek, , ', 'almond', 'tonsil') is a paired nucleus (neuroanatomy), nuclear complex present in the Cerebral hemisphere, cerebral hemispheres of vertebrates. It is c ...

, and thalami as major structures in the

limbic system The limbic system, also known as the paleomammalian cortex, is a set of brain structures located on both sides of the thalamus, immediately beneath the medial temporal lobe of the cerebrum primarily in the forebrain.Schacter, Daniel L. 2012. ''P ...

. The mammillothalamic tract carries signals from the mammillary bodies via the anterior thalamus to support

Clinical significance

Infarction Infarction is tissue death (necrosis) due to Ischemia, inadequate blood supply to the affected area. It may be caused by Thrombosis, artery blockages, rupture, mechanical compression, or vasoconstriction. The resulting lesion is referred to as a ...

of the region including the mammillothalamic tract has been associated with acute

Korsakoff syndrome Korsakoff syndrome (KS) is a disorder of the central nervous system characterized by amnesia, deficits in explicit memory, and confabulation. This neurological disorder is caused by a deficiency of thiamine (vitamin B1) in the brain, and it is ...

History

The mammillothalamic tract was first described by the French physician, Félix Vicq d'Azyr, from whom it takes its alternate name (bundle of Vicq d'Azyr).

References

External links